due to several requests i promised to announce another run of Circuit PCBs, frontpanel components PCBs (eurorack) and eurorack Frontpanels for Thomas Henry's latest Projects (VCO and LFO).

so here we go. i will keep orders until 26 JAN 14.
As always i won't take any money until the goods are ready for delivery.
Please, tell me exactly what you wanted/needed, i.e.
"1 complete set of VCO PCBs/Panels"
or
"2 circuit VCO PCBs
+ 1 frontpanel PCB
+ 1 euro frontpanel"
you get the idea...

don't hesitate to contact me if you are interested in a completed module(handmade for you).

for the Eurorack Frontpanels i would need at least inquiries for a minimum of 30pcs, this is where the proce break kicks in. For less than 30 frontpanels i could not keep the price.

1)
in the original schematic of the VCO frmo thomas henry we three times a resistor R26, whereas R25 is missing completely.
so here are the values corresponding to the PCB labeling that are not covered correctly by the schematic/parts list:
R25 - 300k
R26 - 39k
R55 - 5.6k

2)
when powering from 12V:
R13 = 2k
R27 = 22k
R33 = 137k

3)
when you have a hard time finding a precision trimmer wit 25k, just use 20k. should do the job as well.

4)
Try several LM13700 for best sine. the amplitude might differ quite a bit!

5)
C4 is the timing cap. use a nice C0G/NP0 or a polysterene for better stability.

6)
Parts for the Control PCB
for the pots any vertical mounted 3-pin 9mm pot should do, i used alpha and alps (for the values needed refer to thomas' schematic).
for the jacks i used the PJ301-BM. there is a new high quality version available with berillium copper from
THONK (Europe)
or
ERTHENVAR (USA)

to connect the control board to the cicuit board you will need single row headers and receptables.

if you build the VCO w/o the eurorack frontpanel components PCB you will have to manually wiring it up, which is a very reliable and easy to service solution IMHO. here is a diagram showing how the MTA-100 headers refere to the components:

for troubleshooting it might be helpful to have the silkscreen:
__________

Controller LFO BUILDING NOTES:

the chart below shows how to wire the potentiometers and the jacks, if you don't use the front panel components PCB:

ATTENTION: the PCB omits diode D2. i found the trigger to be fine without it.
however, if you experience occasional double triggers, solder it in parallel to R44.

ATTENTION: the P-JFET 2N5461 comes in different pinouts!
so check the datasheet of the specific brand you use!
(thanks to rosch for this find)

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